Cleanup: Pull some browser keep alive functions into its own file.

chrome/browser/ui/views/auto_keep_alive.h

Index: chrome/browser/ui/views/auto_keep_alive.h
diff --git a/chrome/browser/ui/views/auto_keep_alive.h b/chrome/browser/ui/views/auto_keep_alive.h
index 6efa54d1427ab592b4d9571f917a59ce6f1859b5..40761b987d389ecbe6c6890cd2ccde360006f28e 100644
--- a/chrome/browser/ui/views/auto_keep_alive.h
+++ b/chrome/browser/ui/views/auto_keep_alive.h
@@ -5,8 +5,13 @@
 #ifndef CHROME_BROWSER_UI_VIEWS_AUTO_KEEP_ALIVE_H_
 #define CHROME_BROWSER_UI_VIEWS_AUTO_KEEP_ALIVE_H_
 
+#include "base/memory/scoped_ptr.h"
 #include "ui/gfx/native_widget_types.h"
 
+namespace browser_lifetime {
+class ScopedKeepAlive;
+}
+
 // Class to scoped decrement keep alive count.
 class AutoKeepAlive {
  public:
@@ -14,7 +19,7 @@ class AutoKeepAlive {
   ~AutoKeepAlive();
 
  private:
-  bool keep_alive_available_;
+  scoped_ptr<browser_lifetime::ScopedKeepAlive> keep_alive_;
 
   DISALLOW_COPY_AND_ASSIGN(AutoKeepAlive);
 };